1. Field of the Invention
The present invention relates to a recording device, such as a printer, connected to a host computer to perform operations based on commands from the host computer, and a method for sending recording data from a host computer to the recording device. Particularly, it relates to an interface card detachably mounted in the recording device. The interface card performs data compression and data transfer between the host computer and the recording device.
2. Description of the Related Art
The amount of data exchanged between a host computer and a recording device has been steadily increasing. This is due in part to a higher density of data in recording or printing, an increased number of colors being expressed in the recording or printing output, and an increased variety of recording or printing modes. However, strong demand still exists for higher speeds in recording or printing processes, which requires technologies supporting high speed data transfer.
The amount of data transferred per unit time has been increasing as a result of higher speed data processing in the host computer and recording device. However, the transfer rate will be limited as long as present interfaces widely employed in recording devices (such as RS232C or Centronics) are used.
Under such circumstances, an effective method for decreasing the amount of data to be transferred is for the sender (for example, a host computer) to compress the data with a predetermined algorithm and for the receiver (for example, a recording device) to decompress (restore) the data to its original form.
Incidentally, a printer having an interface card detachably mounted in the printer is well known. Various interface cards correspond to various interfaces between the various host computers and recording devices, such as RS232C, Centronics or USB (Universal Serial Bus). Accordingly, by replacing the interface card, it is possible to be compatible with the various interfaces.
For example, JP-A-8-164640 discloses a print system in which host computers are connected through a network to a printer via a network board connected to the printer. In this print system, the network board has a data decompression control area for decompressing compressed printing data sent from host computers.
However, in a case of communication between a host computer and a recording device using such compressed data, it is required that the receiver decompress the data with the same algorithm as that used by the sender for compression. This requires that the data compression/decompression function provided in the host computer must be the same as that provided in the recording device.
Accordingly, the compression/decompression functions in the recording device must be compatible with the compression/decompression function in the particular host computer that is being used with the recording device.
If any one of the host computer, the interface card or the recording device in use is replaced, or the compression/decompression algorithm is replaced with another algorithm, a problem may arise in which the exchange of compressed data between the host computer and the recording device becomes impossible, or the transfer rate or processing speed become lower.
In addition, if each of the recording device and the interface card has its own compression/decompression function, in order to decrease the time required for data processing, it must determined which of the compression/decompression functions is best for exchanging the compressed data with the host computer.
Therefore, it is an object of the present invention to overcome the aforementioned problems.
An object of the present invention is to provide a solution to the above problem by making the compression/decompression function provided in the recording device easily replaceable so that it is compatible with the compression/decompression function provided in the host computer. Another object is to provide compatibility with a host computer having various compression/decompression functions.
To accomplish the above objects, an interface for communication with a host computer is formed as a card (interface card) in the recording device of the present invention so that it can be replaced independently of the recording device. Specifically, the interface card is detachably connected to a control board, which is mounted in the recording device and has a first controller for controlling the recording device.
A first decompressor for decompressing compressed data received from the host computer is provided in the interface card. This allows selection and replacement of the decompression function in the recording device so that it is compatible with the compression algorithm in the host computer without replacing the recording device as a whole.
A second controller is also provided in the interface card. The second controller allows the first decompressor to decompress the compressed data by comparing data processing performances for decompressing the compressed data between the control board and the interface card.
Furthermore, the present invention may include a control board including a second decompressor capable of decompressing compressed data. The second controller allows either one of the first and second decompressors to decompress the compressed data by first comparing the performances between the control board and the interface card.
This allows a reduction in the time required for data processing by decompressing the compressed data with the decompressor that is more favorable for data decompression performance.
The present invention may include a first compressor provided on the interface card. The first compressor can compress data for communicating with the host computer.
Also, the present invention may include a second compressor mounted in the above recording device and provided on the control board. The second compressor can compress data for communicating with the host computer. In such configuration, the second controller allows either one of said first and second compressors to compress the data, by comparing data processing performances between said control board and said interface card.
This allows a reduction in the time required for data processing by compressing the data using the compressor that is more favorable for data compression performance when the compressed data is sent to the host computer.
Furthermore, in the present invention it is preferable that a plurality of different algorithms for decompressing or compressing the data be provided with each of the first decompressor and the first compressor.
Also, the present invention is directed to a method for sending recording data from a host computer to a recording device. This method is preferably executed under a recording system, in which an interface card, having a first decompressor, is detachably connected to a control board mounted in the recording device, and the host computer communicates with the control board via the interface card.
The method comprises following steps.
(a) determining an algorithm for compressing/decompressing recording data that is available for the host computer and for at least one of the interface card and the control board,
(b) enabling the first decompressor if the control board has no decompressor that can decompress compressed data in accordance with the algorithm determined in the step (a),
(c) if the control board has a second decompressor that can decompress the compressed data, comparing data processing performances for decompressing the compressed data between the control board and the interface card,
(d) in accordance with the result of step (c), enabling either one of the first and second decompressors,
(e) compressing the record data in the host computer in accordance with the algorithm determined in the step (a), and sending the compressed data to the interface card;
(f) if the first decompressor is enabled, decompressing the compressed data in the interface card, and sending the decompressed data to the control board; and
(g) if the first decompressor is disabled, passing the compressed data to the control board; and decompressing the compressed data therein.
The present invention further includes a software program for implementing the method for sending and receiving recording data of the present invention. The software program may be stand-alone, resident on the host computer, recorded on a medium or media readable by the host computer or recording device or embodied in a carrier wave that can be input to the host computer or recording device.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.